Conclusion, that track was definitely cut from the official soundtrack. I decided to look at the format specified ripped tracks (mini2sf) and it's included as '999 Unknown #3.mini2sf'.

I'm definitely happy to listen to it in loop in winamp again, when I heard that track for the first time I was road tripping in the united-states and I just came back from walking in the Great Sand dunes when, later that night just before bedtime, I was parked in the Grand Canyon to play that part of the game, that track have a special place in my heart.